The present invention relates to a process for increasing the efficiency of extraction processes using a liquid dialkyl phosphoric acid as an active extractant for separating soluble metallic values from an aqueous solution.
The use of liquid dialkyl phosphoric acids as active extractants is known.
U.S. Pat. No. 3,607,008 to Chiola et al discloses a process for separating molybdate values from tungstate values using a water insoluble three component organic extractant phase consisting essentially of di-2-ethylhexyl phosphoric acid as an extractant, tributyl phosphate as a solubilizer and a water insoluble hydrocarbon solvent to extract at least a portion of the molybdate values from the feed solution.
U.S. Pat. No. 3,438,768 to Ashbrook et al discloses a process for separating cobalt from nickel in an ammoniacal leach solution with organophosphoric acid compounds including di(2-ethylhexyl) phosphoric acid.
U.S. Pat. No. 3,598,520 to Chiola et al describes a process for the solvent extraction of heavy rare earth elements with an alkyl phosphoric acid.
U.S. Pat. No. 3,591,331 to Chiola relates to a process for producing ammonium metatungstate from ammonium tungstate with an organic extractant solution comprising di-2-ethylhexyl phosphoric acid and a water-insoluble hydrocarbon solvent.
U.S. Pat. No. 3,582,263 to Chiola et al describes a process for the purification of gadolinium wherein the extractant comprises didecyl phosphoric acid, tributyl phosphate and an organic hydrocarbon solvent.
U.S. Pat. No. 3,969,478 to Zelikman et al. describes a process for separating tungsten and molybdenum by the introduction of a stabilizer comprising water soluble phosphorus salts and hydrogen peroxide as a complexing agent. The molybdenum is selectively extracted from the resulting aqueous solution with tri-n-butyl phosphate.
The above patents describe the use of modifiers with the organic extractant or complexing agents with the aqueous feed solution to enhance the extraction of the extractable metallic values into the organic extractant.